This invention relates to the technical field of a light-sensitive material transport device that is to be used in an image recording apparatus which exposes light-sensitive materials to record a latent image.
Heretofore, the image recorded on photographic films such as negatives and reversals (which are hereunder referred to simply as "films") has been commonly printed on light-sensitive materials such as photographic paper by means of direct (analog) exposure, in which projected light from the film is allowed to be incident on the light-sensitive material to achieve its a real exposure.
A new technology has recently been introduced and this is a printer that relies upon digital exposure. Briefly, the image recorded on a film is read photoelectrically, converted to a digital image data (signal) and subjected to various image processing operations to produce image data for recording purposes; recording light that has been modulated in accordance with the image data for the recording purposes is used to scan and expose a light-sensitive material to record a latent image, which is subsequently developed and outputted as a print (photograph). The printer operating on this principle has been commercialized as a digital photoprinter.
In the digital photoprinter, the image on a film is read photoelectrically and gradation correction and other operations are performed by subsequent image (signal) processing to determine exposing conditions. Hence, the digital photoprinter has many capabilities in image processing such as editing of printed images by, for example, assembling a plurality of images or splitting a single image into plural images, as well as color/density adjustment and edge enhancement; as a result, prints can be output after various image processing operations have been performed in accordance with specific uses. In addition, the data on a printed image can be supplied into a computer or the like and stored in recording media such as a floppy disk.
A further advantage of the digital photoprinter is that, compared to the prints produced by the conventional method of direct exposure, those which are output by the digital photoprinter have better image quality in such aspects as resolution and color/density reproduction. Having these features, the digital photoprinter is basically composed of an input machine having a scanner (image reader) and an image processor and an output machine having both an exposing device (image recording apparatus) and a developing device.
In the scanner, projected light carrying the image recorded on the film is photoelectrically read by an image sensor such as a CCD sensor, the image being then captured by photoelectric conversion and sent to the image processor as data for the image on the film (i.e., the image data signal). In the image processor, the image data are subjected to specified image processing operations and the resulting output image data for image recording (i.e., exposing conditions) are sent to the exposing device.
In the exposing device, if it is of a type that relies upon exposure by scanning with an optical beam, the latter is modulated in accordance with the image data sent from the image processor and deflected in a main scanning direction as the light-sensitive material is transported in an auxiliary direction perpendicular to the main scanning direction, whereby a latent image is formed as the result of scan exposure of the light-sensitive material with the optical beam and a back print is also recorded. In the developing device (processor), the exposed light-sensitive material is subjected to development and other specified processing operations so as to output a print which reproduces the image that has been recorded on the film.
In the exposing device, whether it is in the digital photoprinter or an ordinary photoprinter that relies upon "direct" exposure, a virgin light-sensitive material is in the form of a magazine, i.e., a roll contained in a lightproof case. The light-sensitive material is withdrawn out of the magazine loaded in the exposing device and further transported for exposure and other necessary steps.
In the ordinary photoprinter, the light-sensitive material being transported is not cut but remains a web as it is subjected to exposure, back print recording, development, rinse, drying and other necessary steps and only after these steps are complete, the light-sensitive material is cut to individual prints of a specified length.
This process requires that frame information (frame punches) for delineating individual frames (or prints) be formed before or after the exposure of the light-sensitive material. However, the portion of the light-sensitive material where the frame information is formed is simply a waste of space. In addition, frame information have to be formed by special means having a punch, a sensor or the like.
In the photoprinter of the above type, it is considered to cut the light-sensitive material to form a cut sheet in accordance with one sheet of a print and then to expose the cut sheet of the light-sensitive material. In fact, the above method is commercialized in the photoprinter of analog type.
In image recording employing scan exposure, if transport speed for scanning (scanning transport speed) of the light-sensitive material should fluctuate, density of image becomes uneven and, as a result, images of high quality can not be recorded. Therefore, it must be prevented as much as possible that the transport means of the light-sensitive material which is located in the downstream of the scanning transport means will give detrimental effects, for example, load fluctuation on the scanning transport of the light-sensitive material in the course of exposure.
In order to solve the above problems, the image recording apparatus employs several methods such as the method which uses a highly precise scanning transport means and controls this scanning transport means highly precisely, as well as allows the other transport means located in the down stream of the scanning transport means to coincide the speed of the transport by the other transport means with that of the scanning transport highly precisely, the method for forming a loop of the light-sensitive material in an area between the scanning transport means and the other means located in its downstream and the like, whereupon it is prevented that the other transport means will give any influence on the scanning transport.
However, the image recording apparatus that exposes the light-sensitive material after it is cut to sheets is liable to give load fluctuation to the light-sensitive material when the exposed advancing end of the light-sensitive material contacts or is particularly pinched with the downstream transport means. This problem can not be solved by the methods described above, thereby generating uneven scanning transport.
Though this uneven scanning transport is instantaneous and small in scale, an unevenness of the image caused by this uneven scanning transport is a linear unevenness in a main scanning direction, so-called, unevenness in a stripe form. This kind of unevenness is very conspicuous even with a small quantity, i.e., highly noticeable, thereby causing deterioration of the image quality to a great extent.
The exposed light-sensitive material must be smoothly transported to the developing device and the like. However, the virgin light-sensitive material wound in a roll form is loaded in the image recording apparatus so that, even after the light-sensitive material is cut into sheets in accordance with a print size, it still keeps a curling way that prevents a consistent transport of the light-sensitive material. Moreover, curls are not the same in the beginning and in the end portions of the roll of the light-sensitive material. Difference in the form among curls is so large that the consistent transport of the light-sensitive material becomes even more difficult.